The present invention is concerned with novel flake feeds for aquatic animals, especially fish, shrimps and invertebrates, in fresh and sea water and is also concerned with a process for the production thereof.
The production of cereal flakes, for example of rolled oats, for human nutrition with the help of a flaking process is known. Cereal flakes are products of hulling which are preponderantly produced from oats, wheat, rye, barley, millet and rice. For the production of rolled oats, whole grains, as well as groats, are converted into a formable, elastic structure by hydrothermal treatment. The damped material is applied uniformly to a flaking cylinder mill, the pressure of which can be regulated hydraulically. A differentiation is made between large leaf flakes (flakes from the whole grain) with about 0.5 mm rolling-out thickness and small leaf flakes (flakes from groats) with 0.3 mm rolling-out thickness.
Flake feeds are also known for the nutrition of warm and cold water ornamental fish in fresh and sea water. At present, flake feeds for fish are characterised in that they are produced with drum driers. Drum drying is a process for the drying of raw material mixtures which are made liquid to pasty by the addition of water. At the moment, it represents the state of the art and is generally available, Therefore, flake feed for ornamental fish from different manufacturers scarcely differ superficially.
In the case of the production of flake feeds for ornamental fish, an internally heated roller is impinged against uniformly by means of an application device over the whole length of the roller with a previously pasted, viscous raw material mixture (moisture content of the paste about 75%) which, in the case of rotation, the roller takes with it as a thin film on the surface of the roller. During the rotary movement, the water evaporates, which requires a high supply of energy. The dried product is removed with a moisture content of about 2 to 5% by means of knives as a flake strip from the surface of the roller. The final moisture content, which plays an important part for the techanical properties, especially the brittleness of the feed flakes, as well as for the acceptance thereof, can only be adjusted within narrow limits in the case of this process. The thickness of the flake strip produced according to the above-mentioned process is about 0.15 mm, depending upon the raw materials used, and cannot be varied very much. The steam temperature for beating the roller is 120 to 165xc2x0 C. Therefore, heat-labile raw materials, for example enzymes and probiotics, cannot be used. After the production process, a comminution of the cohering flake strip takes place to give a saleable flake feed which consists of individual flakes of differing sizes which are characterised by an uneven form and which find use for the nutrition of aguatic animals, especially of ornamental fish.